Differentiating Responses to Obstructive Sleep Apnoea using Pulse Transit Time

J.Y.A. Foo, S.J. Wilson, G.R. Williams, M.-A. Harris, and D.M. Cooper (Australia)


Measurement and instrumentation, pulse transit time, obstructive sleep apnoea, and sleep-disordered breathing


Conventional overnight polysomnography (PSG) used to determine the respiratory behaviour during sleep can be a complex and expensive procedure. Pulse transit time analysis (PTT) has shown potential to detect obstructive apnoeic and hypopnoeic events in adults. This study was undertaken to determine the potential of PTT to differentiate responses to upper airway obstruction. 103 obstructive respiratory events occurred in PSG studies performed on 11 children (10 male and 1 female, mean age 7.5years). PTT measurements were evaluated against the corresponding PSG results pre-scored by 2 blinded observers. Broadly, there were 2 types of responses. They can be either short period of rapid PTT decreases (Type 1) or prolonged but gradual PTT decreases (Type 2). Type 1 obstructive events showed a mean change of 51.77% (p<0.05), with 8.48ms standard deviation (SD) (p<0.05) and maximal change of 54.80% (p<0.05) from baseline PTT value during tidal breathing. Type 2 events showed a mean 12.01% (p<0.05) change, with 5.28ms SD (p<0.05) and maximal change of 13.32% (p<0.05). PTT was able to categorise different responses during obstructive respiratory events. The results attained here can suggest that PTT can have greater potentials for use in childhood respiratory sleep studies.

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